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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.awt.image;

import java.awt.image.ImageConsumer;
import java.awt.image.ColorModel;
import java.util.Hashtable;
import java.awt.Rectangle;

/**
 * An ImageFilter class for scaling images using the simplest algorithm.
 * This class extends the basic ImageFilter Class to scale an existing
 * image and provide a source for a new image containing the resampled
 * image.  The pixels in the source image are sampled to produce pixels
 * for an image of the specified size by replicating rows and columns of
 * pixels to scale up or omitting rows and columns of pixels to scale
 * down.
 * <p>It is meant to be used in conjunction with a FilteredImageSource
 * object to produce scaled versions of existing images.  Due to
 * implementation dependencies, there may be differences in pixel values
 * of an image filtered on different platforms.
 *
 * @author Jim Graham
 * @see FilteredImageSource
 * @see ImageFilter
 */
public class ReplicateScaleFilter extends ImageFilter {

  /**
   * The width of the source image.
   */
  protected int srcWidth;

  /**
   * The height of the source image.
   */
  protected int srcHeight;

  /**
   * The target width to scale the image.
   */
  protected int destWidth;

  /**
   * The target height to scale the image.
   */
  protected int destHeight;

  /**
   * An <code>int</code> array containing information about a
   * row of pixels.
   */
  protected int srcrows[];

  /**
   * An <code>int</code> array containing information about a
   * column of pixels.
   */
  protected int srccols[];

  /**
   * A <code>byte</code> array initialized with a size of
   * {@link #destWidth} and used to deliver a row of pixel
   * data to the {@link ImageConsumer}.
   */
  protected Object outpixbuf;

  /**
   * Constructs a ReplicateScaleFilter that scales the pixels from
   * its source Image as specified by the width and height parameters.
   *
   * @param width the target width to scale the image
   * @param height the target height to scale the image
   * @throws IllegalArgumentException if <code>width</code> equals zero or <code>height</code>
   * equals zero
   */
  public ReplicateScaleFilter(int width, int height) {
    if (width == 0 || height == 0) {
      throw new IllegalArgumentException("Width (" + width +
          ") and height (" + height +
          ") must be non-zero");
    }
    destWidth = width;
    destHeight = height;
  }

  /**
   * Passes along the properties from the source object after adding a
   * property indicating the scale applied.
   * This method invokes <code>super.setProperties</code>,
   * which might result in additional properties being added.
   * <p>
   * Note: This method is intended to be called by the
   * <code>ImageProducer</code> of the <code>Image</code> whose pixels
   * are being filtered. Developers using
   * this class to filter pixels from an image should avoid calling
   * this method directly since that operation could interfere
   * with the filtering operation.
   */
  public void setProperties(Hashtable<?, ?> props) {
    Hashtable<Object, Object> p = (Hashtable<Object, Object>) props.clone();
    String key = "rescale";
    String val = destWidth + "x" + destHeight;
    Object o = p.get(key);
    if (o != null && o instanceof String) {
      val = ((String) o) + ", " + val;
    }
    p.put(key, val);
    super.setProperties(p);
  }

  /**
   * Override the dimensions of the source image and pass the dimensions
   * of the new scaled size to the ImageConsumer.
   * <p>
   * Note: This method is intended to be called by the
   * <code>ImageProducer</code> of the <code>Image</code> whose pixels
   * are being filtered. Developers using
   * this class to filter pixels from an image should avoid calling
   * this method directly since that operation could interfere
   * with the filtering operation.
   *
   * @see ImageConsumer
   */
  public void setDimensions(int w, int h) {
    srcWidth = w;
    srcHeight = h;
    if (destWidth < 0) {
      if (destHeight < 0) {
        destWidth = srcWidth;
        destHeight = srcHeight;
      } else {
        destWidth = srcWidth * destHeight / srcHeight;
      }
    } else if (destHeight < 0) {
      destHeight = srcHeight * destWidth / srcWidth;
    }
    consumer.setDimensions(destWidth, destHeight);
  }

  private void calculateMaps() {
    srcrows = new int[destHeight + 1];
    for (int y = 0; y <= destHeight; y++) {
      srcrows[y] = (2 * y * srcHeight + srcHeight) / (2 * destHeight);
    }
    srccols = new int[destWidth + 1];
    for (int x = 0; x <= destWidth; x++) {
      srccols[x] = (2 * x * srcWidth + srcWidth) / (2 * destWidth);
    }
  }

  /**
   * Choose which rows and columns of the delivered byte pixels are
   * needed for the destination scaled image and pass through just
   * those rows and columns that are needed, replicated as necessary.
   * <p>
   * Note: This method is intended to be called by the
   * <code>ImageProducer</code> of the <code>Image</code> whose pixels
   * are being filtered. Developers using
   * this class to filter pixels from an image should avoid calling
   * this method directly since that operation could interfere
   * with the filtering operation.
   */
  public void setPixels(int x, int y, int w, int h,
      ColorModel model, byte pixels[], int off,
      int scansize) {
    if (srcrows == null || srccols == null) {
      calculateMaps();
    }
    int sx, sy;
    int dx1 = (2 * x * destWidth + srcWidth - 1) / (2 * srcWidth);
    int dy1 = (2 * y * destHeight + srcHeight - 1) / (2 * srcHeight);
    byte outpix[];
    if (outpixbuf != null && outpixbuf instanceof byte[]) {
      outpix = (byte[]) outpixbuf;
    } else {
      outpix = new byte[destWidth];
      outpixbuf = outpix;
    }
    for (int dy = dy1; (sy = srcrows[dy]) < y + h; dy++) {
      int srcoff = off + scansize * (sy - y);
      int dx;
      for (dx = dx1; (sx = srccols[dx]) < x + w; dx++) {
        outpix[dx] = pixels[srcoff + sx - x];
      }
      if (dx > dx1) {
        consumer.setPixels(dx1, dy, dx - dx1, 1,
            model, outpix, dx1, destWidth);
      }
    }
  }

  /**
   * Choose which rows and columns of the delivered int pixels are
   * needed for the destination scaled image and pass through just
   * those rows and columns that are needed, replicated as necessary.
   * <p>
   * Note: This method is intended to be called by the
   * <code>ImageProducer</code> of the <code>Image</code> whose pixels
   * are being filtered. Developers using
   * this class to filter pixels from an image should avoid calling
   * this method directly since that operation could interfere
   * with the filtering operation.
   */
  public void setPixels(int x, int y, int w, int h,
      ColorModel model, int pixels[], int off,
      int scansize) {
    if (srcrows == null || srccols == null) {
      calculateMaps();
    }
    int sx, sy;
    int dx1 = (2 * x * destWidth + srcWidth - 1) / (2 * srcWidth);
    int dy1 = (2 * y * destHeight + srcHeight - 1) / (2 * srcHeight);
    int outpix[];
    if (outpixbuf != null && outpixbuf instanceof int[]) {
      outpix = (int[]) outpixbuf;
    } else {
      outpix = new int[destWidth];
      outpixbuf = outpix;
    }
    for (int dy = dy1; (sy = srcrows[dy]) < y + h; dy++) {
      int srcoff = off + scansize * (sy - y);
      int dx;
      for (dx = dx1; (sx = srccols[dx]) < x + w; dx++) {
        outpix[dx] = pixels[srcoff + sx - x];
      }
      if (dx > dx1) {
        consumer.setPixels(dx1, dy, dx - dx1, 1,
            model, outpix, dx1, destWidth);
      }
    }
  }
}
